A passive optical network (PON) technology is one of fiber to the home (FTTH) technologies that are most widely used currently. Existing PONs may be classified into a power-splitting passive optical network and a wavelength division multiplexing passive optical network (WDMPON) according to a signal distribution manner. An existing broadband passive optical network (BPON), gigabit-capable passive optical network (GPON), Ethernet passive optical network (EPON), and the like are power-splitting passive optical networks. The WDMPON based on a wavelength division multiplexing technology implements uplink access by using the wavelength division multiplexing technology, is capable of providing a relatively high operating bandwidth, and implements symmetric broadband access.
In various PON systems, an 8b/10b encoding scheme is mainly adopted; however, adopting this encoding scheme has a bandwidth overhead up to 25%, and adopting this encoding scheme cannot implement a line detection function for an online service. Therefore, how to improve the existing encoding scheme to reduce a system overhead and implement the line detection function in a PON system becomes an urgent problem to be resolved.